Conventionally, as a tire traveling test device which evaluates traveling property of tires, those using an endless flat belt (herebelow referred to as belt) which imitates a flat road surface have been known. In such traveling test devices, a belt is spanned over two drums. Specifically, the belt mentioned above is spanned over two drums in a manner separated into upper side and lower side, the upper side belt constituting a ground contact face for tire which allows a tire a ground contact. On the other hand, the belt, in the back side of this ground contact face for tire, is provided with a load support device which prevents the belt from bending, and supports a tire load.
The load support device is configured to have a structure in which a support liquid, such as a pressurized water or oil, is supplied between the upper face (belt supporting face) of this load support device and the lower face of the belt, in order to smoothly support running of the belt. That is, the load support device comprises a function to support the belt by supplying the support liquid to the contacting face of the belt to thereby float the belt.
As a traveling test device which adopt the technique of floating a belt from a load support device by use of a pressurized support liquid in this way, those disclosed in the Patent Document 1 and Patent Document 2 have been known.
These traveling test devices of the Patent Document 1 and the Patent Document 2 both have a structure which supplies the support liquid by providing plural circular holes on the upper face of the load support device, and blowing out the pressurized support liquid from these plural circular holes. In a case of adopting such method of supplying a support liquid, the circular holes will be closed in those regions where a tire is in ground contact, to suppress the amount of the support liquid to be blown out according to a ground contacting pressure, in the upper face of the load support device. However, the support liquid easily leaks out from the circular holes disposed in a region where a tire is not in ground contact, or in a region where a ground contact pressure of the tire is low. This causes, further enhanced by a force of the support liquid blown out from the circular holes, the belt to be further floated from the upper face of the load support device, and the floating of the belt becomes further excessive to require a significant amount of support liquid to be continuously supplied, which brings about a lowering of supplying pressure of the support liquid, or causes an increase of energy loss.
In order to lower such energy loss, in the traveling test device of the Patent Document 1, plural chambers are constructed in a liquid pressure receiving unit of the belt so as to be able to supply the each chamber with support liquid each different in liquid pressure. In such a structure, it is possible to control a liquid pressure of the support liquid to be high in a part where a tire is in ground contact, and to control a liquid pressure of the support liquid to be low in a part where a tire is not in ground contact, and accordingly, it becomes possible to avoid a wasteful use of the support liquid and control the energy loss to be small.
The traveling test device of the Patent Document 2 is provided with an orifice between circular holes which blow out a pressurized support liquid and a supply unit which supplies these circular holes with a high pressure support liquid. By providing such an orifice, a wasteful blowing out of the support liquid from the circular holes is controlled by a pressure loss at the time of passing through the orifice, to inhibit the wasteful use of the support liquid, and as a result, it becomes possible to lower the energy loss.